Painting in pastels means working in a dry medium with pure pigments. However, pastel crayons are more frequently used. Both the material and the picture thus made are called "pastel". To make pastel crayons, color pigments are mixed with an aqueous binder such as gum tragacanth. The resulting paste [Italian: "pasta"; "pastello" = a formed pigmented paste] is then formed into crayons. In painting with pastel, the color is applied in a powdery layer to the ground and rubbed with the fingers or a stump (stomp) to smudge and blend it, which results in exquisitely subtle gradations of color. The possibilities for correction are unlimited because pastel colors are easy to remove or cover over. Pastel painting provides many possibilities for linking drawing with painting. A pastel can have the character both of a drawing (drawing in pastel) or of a painting with color surfaces that are worked into each other. The support for pastel painting can be pastel paper, cardboard or canvas but must have a rough texture, enough "tooth" to take and hold the color pigments. Nevertheless, pastels are very sensitive, they rub off very easily and are sensitive to light. Nor should they be shaken because the slightest motion causes the pigment powder to detach itself from the support. Pastel paintings must, therefore, always be framed behind glass to protect them. To make the pigments adhere better, they can also be sprayed lightly with a fixative. However, this always impairs the purity, lightness and delicacy of the colors in a pastel painting.